problem with avx instruction

[aw27]

I just tried it, was not expecting it to be so easy, and simply worked on my SandyBridge which does not support AVX2.

sde -- myTest.exe

[Siekmanski]

Hi Jochen,

vpshufd = 512 bit.
vshufpd = 256 bit.

[aw27]

Hi Jochen,

vpshufd = 512 bit.
vshufpd = 256 bit.

vpshufd is AVX2 instruction not AVX-512 instruction. AVX-512 added BW, VL, F extensions.

[jj2007]

I got SDE running, but it seems a bit buggy. Olly stops in the middle of nowhere, etc. However, the simple demo manages to go beyond the "illegal instruction" line when e.g. -skl is specified.

But -slm chokes with SDE-ERROR: Executed instruction not valid for specified chip (SILVERMONT): 0x401201: vmovdqa

[Siekmanski]

aw27, you are right, vpshufd is avx2 and not a 512 bit instruction.  :icon_redface: I'm awake now.

[aw27]

I got SDE running, but it seems a bit buggy. Olly stops in the middle of nowhere, etc. However, the simple demo manages to go beyond the "illegal instruction" line when e.g. -skl is specified.

But -slm chokes with SDE-ERROR: Executed instruction not valid for specified chip (SILVERMONT): 0x401201: vmovdqa

I have not explored much, but is good to know we have something when we have nothing else.
However, I believe it is not compatible with debuggers, because emulators set the processor into single step mode.

"The Silvermont supports the SSE4.2 instruction set, but not AVX and AVX2" - Agner Fog

[aw27]

I'm awake now.

Good morning.  :t

[jj2007]

I believe it is not compatible with debuggers, because emulators set the processor into single step mode.

Once I got it running with Olly, but after a small change somewhere it stopped working. I see your logic but not sure what it means in practice.

[aw27]

It practice may mean that debugging emulated code may depend on facilities provided by the emulator.
I dont know if you have already read the Help or the Manual. :icon_cool: